Inigo Martínez authored Dec 15, 2017 and Thomas Haller committed Dec 16, 2017

There are three headers `nm-secret-agent-old.h`,
`nm-vpn-plugin-old.h`, and `nm-vpn-service-plugin.h`, which are
named as no introspection headers. However, these files also
join to the rest headers to generate introspection data.

This patch merges those no introspection headers with the public
headers.